"It was part of our fight against a secular system," he told AFP by telephone from an undisclosed location.

"We will carry out more such attacks in future."

Taliban insurgents have led a bloody campaign against the Pakistani state in recent years. They have carried out hundreds of attacks on security forces and government targets, mainly in the northwest.

An eyewitness told AFP by telephone that the vehicle hit by the bomb was transformed into scorched metal.

"I collected human remains including hands and legs from the site after the attack," he said on condition of anonymity.

Body parts and soldiers' personal belongings littered the scene.

"I also helped rescue workers in moving injured people to ambulances," the witness added.

Bannu has been the scene of several past attacks on security forces.

Pakistani troops have for years been battling homegrown insurgents in the tribal belt, which Washington considers the main hub of Taliban and Al-Qaeda militants plotting attacks on the West and in Afghanistan.

The Pakistani Taliban, other militant affiliates and Al-Qaeda-linked networks all have strongholds in the country's northwest, particularly in the semi-autonomous tribal areas on the Afghan border.

Pakistan, which joined the US-led "war on terror" in 2001, has since July 2007 been gripped by a local Taliban-led insurgency concentrated largely in the northwest.

It says more than 40,000 people have been killed in Pakistan since 2001 by militants who oppose Islamabad's US alliance.

A bomb claimed by the Pakistani Taliban killed 20 soldiers and wounded more than 30 when it ripped through a military convoy in the restive northwest on Sunday, officials said.

The attack happened in the city of Bannu, near the North Waziristan tribal region which is a known stronghold of militants linked to the Taliban and Al-Qaeda.

"A vehicle-borne improvised explosive device caused the blast," a senior military official told AFP, adding the exact circumstances were unclear.

"The explosion took place in one of the vehicles of the convoy, killing 20 soldiers and wounding more than 30," he said on condition of anonymity.

The official said the convoy was about to leave for the town of Razmak in North Waziristan when the blast hit one of the civilian vehicles hired to move troops.

"It was part of our fight against a secular system," he told AFP by telephone from an undisclosed location.

"We will carry out more such attacks in future."

Taliban insurgents have led a bloody campaign against the Pakistani state in recent years. They have carried out hundreds of attacks on security forces and government targets, mainly in the northwest.

An eyewitness told AFP by telephone that the vehicle hit by the bomb was transformed into scorched metal.

"I collected human remains including hands and legs from the site after the attack," he said on condition of anonymity.

Body parts and soldiers' personal belongings littered the scene.

"I also helped rescue workers in moving injured people to ambulances," the witness added.

Bannu has been the scene of several past attacks on security forces.

Pakistani troops have for years been battling homegrown insurgents in the tribal belt, which Washington considers the main hub of Taliban and Al-Qaeda militants plotting attacks on the West and in Afghanistan.

The Pakistani Taliban, other militant affiliates and Al-Qaeda-linked networks all have strongholds in the country's northwest, particularly in the semi-autonomous tribal areas on the Afghan border.

Pakistan, which joined the US-led "war on terror" in 2001, has since July 2007 been gripped by a local Taliban-led insurgency concentrated largely in the northwest.

It says more than 40,000 people have been killed in Pakistan since 2001 by militants who oppose Islamabad's US alliance.